Process for relaxing keratin fibres

ABSTRACT

The invention relates to a process for relaxing keratin fibres by applying to the keratin fibres a relaxing composition containing at least one denaturing agent with a molecular mass of greater than 18.1 g/mol, present in a molar concentration of between 1M and 8M, and raising the temperature of the keratin fibres to a temperature of between 110 and 250° C.

REFERENCE TO PRIOR APPLICATIONS

This application claims priority to U.S. provisional application60/646,616 filed Jan. 26, 2005, and to French patent application 0452775filed Nov. 26, 2004, both incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a process for relaxing keratin fibres with heatand at least one denaturing agent.

Additional advantages and other features of the present invention willbe set forth in part in the description that follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from the practice of thepresent invention. The advantages of the present invention may berealized and obtained as particularly pointed out in the appendedclaims. As will be realized, the present invention is capable of otherand different embodiments, and its several details are capable ofmodifications in various obvious respects, all without departing fromthe present invention. The description is to be regarded as illustrativein nature, and not as restrictive.

BACKGROUND OF THE INVENTION

Two techniques are used to obtain permanent reshaping of the hair. Theyare based on cleavage of the disulfide covalent bonds present in keratin(cystine):

the first consists, in a first stage, in performing this opening of thedisulfide bonds using a composition containing a reducing agent, andthen after, preferably, having rinsed the hair, in reconstituting, in asecond stage, the said disulfide bonds by applying to the hair, that hasbeen placed under tension beforehand by means of rollers or the like orshaped or smoothed out by other means, an oxidizing composition alsoknown as a fixer, so as to give the head of hair the desired shape. Thistechnique makes it possible either to make the hair wavy or to relax it,uncurl it or smooth it out;

the second consists in performing a “lanthionization” operation, using acomposition containing a base belonging to the hydroxide family. Itleads to the replacement of the disulfide bonds (—CH2-S—S—CH2-) withlanthionine bonds (—CH2-S—CH2-). This lanthionization operation involvestwo consecutive chemical reactions:

The first reaction consists of a beta-elimination on cystine broughtabout by a hydroxide ion, leading to the cleavage of this bond and tothe formation of dehydroalanine.

The second reaction is a reaction of the dehydroalanine with a thiolgroup. Specifically, the double bond of the dehydroalanine formed is areactive double bond. It can react with the thiol group of the cysteineresidue that has been released to form a new bond known as a lanthioninebridge or bond or residue.

Relative to the first technique using a reducing agent, thislanthionization technique does not require a fixing step, since theformation of the lanthionine bridges is irreversible. It is thusperformed in a single step and makes it possible either to make the hairwavy or to relax it, uncurl it or smooth it out. However, it is mainlyused for relaxing naturally frizzy hair.

For the first technique, the reducing compositions generally used forthe first step of a permanent-waving or relaxing operation containthiols, sulfites or bisulfites as reducing agent. These agents aregenerally used in essentially aqueous medium at concentrations ofbetween 0.5 and 1M to obtain good opening of the disulfide bonds. Amongthe thiols, those commonly used are thioglycolic acid, cysteamine,glyceryl monothioglycolate, thiolactic acid and cysteine. Thioglycolicacid is particularly effective for reducing the disulfide bonds ofkeratin at alkaline pH, especially in the form of ammoniumthioglycolate, and is the product most widely used in permanent-waving(“hair waving”). However, it has been found that thioglycolic acid mustbe used in a sufficiently basic medium (in practice at a pH of between8.5 and 9.5) if it is desired to obtain curliness of satisfactoryintensity. Besides the drawback of giving off an unpleasant odourrequiring the use of more or less efficient fragrances to mask theodours, the use of a thiol at alkaline pH also leads to degradation ofthe fibre and most particularly to impairment of artificial colorations.

Sulfites or bisulfites are mainly used for relaxing. They have similardrawbacks to thiols, with less efficacy.

Thiols and sulfites (or bisulfites) also have the drawback of havingpoor stability in aqueous solution.

In general, the durability of the reshaping effects obtained with thiolsand sulfites by reduction of disulfides followed by fixing is judged tobe very much inferior to that which may be obtained via thelanthionization technique.

For the second technique, the compositions generally used to perform thelanthionization contain as base a hydroxide such as sodium hydroxide,guanidinium hydroxide or lithium hydroxide. These lanthionization activeagents, which allow the disulfide bonds to be opened via abeta-elimination mechanism, are generally used as a water-oil emulsionat concentrations of between 0.4 and 0.6M, by leaving them to actgenerally for 10 to 15 minutes at room temperature. Sodium hydroxideremains the agent most widely used. Guanidinium hydroxide is now thepreferred compound for many compositions. These two hydroxides, sodiumhydroxide and guanidinium hydroxide, are the two main agents used forrelaxing or uncurling naturally frizzy hair. They have severaladvantages over ammonium thioglycolate and sulfites, in particular anabsence of unpleasant odour, the fact that only one implementation stepis required (shorter treatment time), and a much greater durability andefficacy of the reshaping of the hair.

However, these hydroxides have the major drawback of being caustic. Thiscausticity affects the scalp by causing irritation, which mayoccasionally be severe. This may partially be remedied by first applyingto the scalp a fatty protective cream often referred to as a “base” or“base cream”, the word “base” in this instance not having the meaning ofa basic agent in the chemical sense. When the protective cream iscombined with hydroxide in a single composition, it is generally knownas a “no-base” cream, as opposed to the above name. This “no-base”technology is preferred.

The causticity of hydroxides also affects the condition of the hair byfirstly giving it a coarse feel and secondly making it much morefragile, this fragility possibly going as far as flaking or evenbreaking, or even the dissolution of the hair if the treatment isprolonged. In certain cases, hydroxides also cause decolorization of thenatural colour of the hair.

Formulations containing sodium hydroxide are generally known as “lyerelaxers” and those not containing it are known as “no-lye relaxers”.

The main “no-lye” relaxing formulations use guanidinium hydroxide. Sinceguanidinium hydroxide is unstable, it is generated extemporaneously bymixing guanidine carbonate and a source of very sparingly solublehydroxide such as calcium hydroxide. The reaction between these twocompounds leads to the formation of guanidinium hydroxide and calciumcarbonate, which precipitates in the composition. The presence of thisprecipitate makes the final rinsing of the hair much more difficult andleaves on the hair and the scalp mineral particles that give it a coarsefeel and an unattractive appearance resembling dandruff. The recentsuccess of guanidinium hydroxide (“no-lye”) in the face of sodiumhydroxide (“lye”) appears to arise from better relaxing efficacy andbetter skin tolerance. However, these technologies using bases of thehydroxide family remain very aggressive for the hair and the scalp andrequire very strict control of the application time to avoid excessiveirritation and impairment of the hair, which may go as far as breakingof the hair. This aggressiveness arising from the causticity ofhydroxides is just reason for these hair lanthionization compositionsnot being used for permanent-waving (“hair waving”), but being reservedfor relaxing (“hair straightening” or “hair relaxing”).

Furthermore, hydroxides are known to be good agents for hydrolysingamide functions (cf. for example March's Advanced Organic Chemistry, 5ed., Wiley Interscience, New York, “Hydrolysis of Amides” pages 474 etseq.), which thus lead to cleavage of the peptide bonds via directnucleophilic attack. It is thus probable that the impairments observedon the hair and keratin materials in the broad sense are largely due topartial hydrolysis of the amide bonds of keratin.

There is thus a real need for relaxing compositions that are markedlyless aggressive to the hair.

Various studies have been conducted in order to overcome the drawbacksof both reducing agents (first technique) and/or of hydroxides (secondtechnique).

Thus, to replace thioglycolic acid, numerous reducing agents have beenproposed, but thioglycolic acid in its ammonium thioglycolate formremains both the compound of reference and the compound most widely usedin cosmetic formulations, both for shaping and for straightening.

It has also been proposed in numerous patents to combine common reducingagents (thiols, sulfites or bisulfites) with urea or alkylureas toreduce the irritation and damage caused on the hair both by shaping andby relaxing. Reference will be made, for example, to:

patent application CA 1315204, which describes a composition containingammonium thioglycolate (5.5-11.5%) and urea or a monoalkylurea (1-3%)for shaping the hair,

patent application U.S. Pat. No. 3,847,165, which describes acomposition containing ammonium thioglycolate (1.2-1.4M) and urea(2.0-2.7M) for shaping the hair at acidic pH,

patent application NL 6 410 355, which describes a compositioncontaining a sulfite (0.8-1.5M) and urea (0.6-3.0M) for shaping andrelaxing the hair,

patent application JP 2000/229 819, which describes a compositioncontaining a sulfite or bisulfite (0.5-15%), urea (0.5-15%) and analcohol (ethanol and/or isopropanol, 1-30%) for shaping and relaxing thehair.

It has also been proposed in numerous patents to combine hydroxides,serving as lanthionization active agent, with certain additivesgenerally serving to protect the hair. Mention will be made, forexample, of:

patent application WO 2002/003 937, which describes a compositioncontaining C3-C5 monosaccharides,

patent application WO 2001/064 171, which describes a compositioncontaining complexing agents,

U.S. Pat. No. 5,641,477, which describes a composition containing ahydrogenated starch hydrolysate,

patent application WO 02/085 317, which describes a compositioncontaining organic nucleophiles, which react during the second step withthe dehydroalanine formed with hydroxides, to give new bridges.

Although all these proposals lead to more or less marked improvements,they do not make it possible to significantly reduce the damage causedby the causticity itself of hydroxides.

As indicated above, the use of reducing agents leads to mediocredurability for relaxing or uncurling, and the use of hydroxides, onaccount of their causticity, limits their use to the field of relaxing.

SUMMARY OF THE INVENTION

After extensive studies, it has now been discovered, entirelysurprisingly and unexpectedly, that the hair can be durably relaxed bycombining the action of a denaturing agent and by heating to atemperature above 110° C. Excellent results in terms of relaxing, haircosmetic properties and fibre integrity are thus obtained.

Definitions

According to the invention, the term “keratin fibres” means fibres ofhuman or animal origin such as head hair, body hair, the eyelashes,wool, angora, cashmere or fur. Although the invention is not limited toparticular keratin fibres, reference will nevertheless be made moreparticularly to head hair.

According to the invention, the term “relaxing” covers the relaxing,straightening or uncurling, and includes such effects on, e.g.,Caucasian and African hair. According to the invention, the term “torelax” means to relax, to straighten or to uncurl.

The term “denaturing agent” includes those compounds specificallyidentified as such herein and means an organic or mineral compoundcontaining both at least one electron-donating site of basic ornucleophilic nature and at least one electron-withdrawing site of acidicor electrophilic nature, which interact with the weak bonds of keratin.

According to the invention, a denaturing agent is a compound capable ofreducing the optical rotation of a model protein, for instance bovineserum albumin, by at least 70 and/or 50 at 579 nm, the measurementsbeing taken after 3 hours of incubation at 37° C., using a polarimeter,as described in Biochemistry 2 (1), 47-57, 1963:

either in 0.05M pH 7.6 TRIS buffer,

or in a 5.45M urea solution when the solubility of the compound isinsufficient in 0.05M pH 7.6 TRIS buffer.

The compound is considered as being a denaturing agent according to theinvention if the reduction in the optical rotation is at least 70 in0.05M pH 7.6 TRIS buffer and/or at least 5° in 5.45M urea solution.

The term “weak bonds of keratin” means all of the non-covalent bonds,such as:

the saline bonds resulting from coulombic interactions between thefunctional groups present on the side chains of amino acids, hydrogenbonds, which are established between the amino acids especially viaoxygen and hydrogen atoms,

hydrophobic bonds resulting from the tendency of the non-polar chains ofamino acids to associate in order to minimize the contacts with water.

The term “heating means” is a term invoking 35 U.S.C. 112, paragraph 6,and is defined as any means for heating keratin fibres to a temperatureof at least 110° C., such as heating irons, for example flat or roundirons, microwave generators, sources of infrared radiation, etc. Theterms “heater” and “heaters” include all of these examples but are notterms implicating 35 U.S.C. 112, paragraph 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Without being bound by theory, the inventor believes that there is acombined action, on the keratin fibres, of a denaturing agent and of theaction of a heater or a heating means, which allows the fibres to beeffectively and durably relaxed.

The Inventor has found that it is possible to overcome the drawbacks ofthe prior art and to meet the abovementioned objectives by performing aprocess for relaxing keratin fibres comprising:

applying to the keratin fibres a relaxing composition comprising atleast one denaturing agent preferably having a molecular mass (weight)of greater than 18.1 g/mol, present in a molar concentration of between1M and 8M in said composition, and

raising the temperature of the keratin fibres, for example using aheater or heating means, to a temperature of between 110 and 250° C.

These two steps can be accomplished in any order, or simultaneously.Preferably, they are accomplished in the order stated above.

A molar concentration of between 1M and 8M generally corresponds to aweight concentration of between about 6% and about 80% relative to thetotal weight of the composition.

Thus, one subject of the invention is a process for relaxing keratinfibres comprising:

applying to the keratin fibres a relaxing composition comprising atleast one denaturing agent with a molecular mass of greater than 18.1g/mol, present in a molar concentration of between 1M and 8M,

then raising the temperature of the (treated) keratin fibres, using aheater or heating means, to a temperature of between 110 and 250° C.

Optionally, the hair can be dried to some extent after treatment withthe relaxing composition prior to application of heat to raise thetemperature of the keratin fibres, for example by wiping with a towel,etc. However, it is preferred that the hair have remaining thereon atleast some denaturing agent when heat is applied so as to obtain thebenefits of the present invention.

Preferably, the relaxing composition comprises between 2M and 8M of thesaid denaturing agent; this corresponds to a weight concentration ofbetween about 12% and about 80%, relative to the total weight of thecomposition, of the said denaturing agent.

Advantageously, the temperature is raised using a heater or by heatingmeans to a temperature of between 120° C. and 220° C. and moreadvantageously between 140° C. and 220° C.

Advantageously, the molar mass of the denaturing agent is between 40 and600 g/mol.

Preferably, the relaxing composition is applied to wet keratin fibres.

As noted above, the removal of excess relaxing composition, for exampleusing a towel, may advantageously be inserted between the act ofapplying the relaxing composition and the act of raising thetemperature.

Preferably, the denaturing agent is chosen from protein-denaturingagents such as ureas, guanidines, amidines, urethanes, aromaticmonohydroxylated, dihydroxylated, trihydroxylated or polyhydroxylatedderivatives, nitrogen heterocycles of the imidazole or triazole family,carboxylic acids and amide and thioamide derivatives thereof, thioureas,amino acids, alcohols, polyols, amine oxides, surfactants containingsugar, choline, deoxycholine or polyethylene glycol units, metal saltsand sulfamides.

The denaturing agent is advantageously a urea or a guanidine.

As “urea” that may be used as relaxing active agent, this term refers toany derivative comprising in its chemical formula a carbonyl groupsimply bonded to 2 nitrogen atoms. These ureas are more particularlyselected from the compounds of general formulae (I) and (II) below:

in which:

R1, R2, R3 and R4 represent, independently:

(i) a hydrogen atom, or

(ii) a linear or branched lower C1-C4 alkyl or alkenyl radical,optionally substituted with a radical chosen from: hydroxyl, amino,dimethylamino, carboxyl or carboxamide or N-methylcarboxamide.

When R1, R2 and R3 represent a hydrogen atom, R4 may also denote aradical chosen from the following: carboxamide; methoxy; ethoxy;1,2,4-triazolyl; cyclopentyl; methoxycarbonyl; ethoxycarbonyl;CO—CH═CH—COOH; phenyl optionally substituted with a chlorine atom or ahydroxyl radical; benzyl; or 2,5-dioxo-4-imidazolidinyl.

When R1 and R3 represent a hydrogen atom, R2 may also represent ahydrogen atom or a methyl or ethyl radical and R4 an acetyl radical.

When R1=R2=H, R3 and R4 may also form, with the nitrogen atom that bearsthem, a piperidine or 3-methylpyrazole or 3,5-dimethylpyrazole ormaleimide ring.

Finally, R1 and R2, and also R3 and R4, may also form, with the nitrogenatom that bears them, an imidazole ring.

in which:

R5 and R6 represent, independently of each other:

(i) a hydrogen atom, or

(ii) a linear or branched C1-C4 lower alkyl radical, optionallysubstituted with a radical chosen from: hydroxyl, amino, dimethylamino,carboxyl or carboxamide,

and A represents the radicals: CH2-CH2 or CH═CH or CH2-CO or CO—NH orCH═N or CO—CO or CHOH—CHOH or (HOOC)CH—CH or CHOH—CO or CH2-CH2-CH2 orCH2-NH—CO or CH═C(CH3)—CO or NH—CO—NH or CH2-CH2-CO or CH2-N(CH3)—CH2 orNH—CH2-NH or CO—CH(CH3)—CH2 or CO—CH2-CO or CO—NH—CO or CO—CH(COOH)—CH2or CO—CH═C(COOH) or CO—CH═C(CH3) or CO—C(NH2)═CH or CO—C(CH3)═N orCO—CH═CH or CO—CH═N or CO—N═CH.

Among the compounds of formula (I), mention may be made especially ofthe following preferred compounds:

urea

methylurea

ethylurea

propylurea

isopropylurea

n-butylurea

sec-butylurea

isobutylurea

tert-butylurea

cyclopentylurea

1-ethoxyurea

2-hydroxyethylurea

N-(2-hydroxypropyl)urea

N-(3-hydroxypropyl)urea

N-(2-dimethylaminopropyl)urea

N-(3-dimethylaminopropyl)urea

1-(3-hydroxyphenyl)urea

benzylurea

N-carbamoylmaleimide

biuret

N-carbamoylmaleamic acid

1-piperidinecarboxamide

1,2,4-triazol-4-ylurea

hydantoic acid

methyl allophanate

ethyl allophanate

acetylurea

2-hydroxyethyleneurea

2-(hydroxyethyl)ethyleneurea

N-allyl-N′-ethylurea

diallylurea

2-chloroethylurea

N,N-dimethylurea

N,N-diethylurea

N,N-dipropylurea

1-cyclopentyl-1-methylurea

1,3-dimethylurea

1,3-diethylurea

1,3-bis(2-hydroxyethyl)urea

1,3-bis(2-hydroxypropyl)urea

1,3-bis(3-hydroxypropyl)urea

1,3-dipropylurea

1-ethyl-3-propylurea

1-sec-butyl-3-methylurea

1-isobutyl-3-methylurea

1-cyclopentyl-3-methylurea

N-acetyl-N′-methylurea

trimethylurea

1-butyl-3,3-dimethylurea

tetramethylurea

benzylurea

Among the compounds of formula (II), mention may be made especially ofthe following preferred compounds:

parabanic acid

1,2-dihydro-3-H-1,2,4-triazol-2-one

barbituric acid

uracil

1-methyluracil

3-methyluracil

5-methyluracil

1,3-dimethyluracil

5-azauracil

6-azauracil

5-fluorouracil

6-fluorouracil

1,3-dimethyl-5-fluorouracil

5-aminouracil

6-aminouracil

6-amino-1-methyluracil

6-amino-1,3-dimethyluracil

4-chlorouracil

5-chlorouracil

5,6-dihydrouracil

5,6-dihydro-5-methyluracil

2-imidazolidone hydrate

1-methyl-2-imidazolidinone

1,3-dimethyl-2-imidazolidinone

4,5-dihydroxyimidazolidin-2-one

1-(2-hydroxyethyl)-2-imidazolidinone

1-(2-hydroxypropyl)-2-imidazolidinone

1-(3-hydroxypropyl)-2-imidazolidinone

4,5-dihydroxy-1,3-dimethylimidazolidin-2-one

1,3-bis(2-hydroxyethyl)-2-imidazolidinone

2-imidazolidone-4-carboxylic acid

1-(2-aminoethyl)-2-imidazole

4-methyl-1,2,4-triazoline-3,5-dione

2,4-dihydroxy-6-methylpyrimidine

1-amino-4,5-dihydro-1H-tetrazol-5-one

hydantoin

1-methylhydantoin

5-methylhydantoin

5,5-dimethylhydantoin

5-ethylhydantoin

5-n-propylhydantoin

5-ethyl-5-methylhydantoin

5-hydroxy-5-methylhydantoin

5-hydroxymethylhydantoin

1-allylhydantoin

1-aminohydantoin

hydantoin 5-acetic acid

4-amino-1,2,4-triazolone-3,5-dione

hexahydro-1,2,4,5-tetrazine-3,6-dione

5-methyl-1,3,5-triazinon-2-one

1-methyltetrahydropyrimidin-2-one

2,4-dioxohexahydro-1,3,5-triazine

urazole

4-methylurazole

orotic acid

dihydroxyorotic acid

2,4,5-trihydroxypyrimidine

2-hydroxy-4-methylpyrimidine

4,5-diamino-2,6-dihydroxypyrimidine

barbituric acid

1,3-dimethylbarbituric acid

cyanuric acid

1-methylhexahydropyrimidine-2,4-dione

1,3-dimethyl-3,4,5,6-tetrahydro-2-1H-pyrimidinone

5-(hydroxymethyl-2,4-(1H,3H)-pyrimidinedione

2,4-dihydroxypyrimidine-5-carboxylic acid

6-azathymine

5-methyl-1,3,5-triazinan-2-one

N-carbamoylmaleamic acid

alloxan monohydrate

Among the compounds of formula (I) that may especially be mentioned arethe following particularly preferred compounds:

urea

methylurea

ethylurea

propylurea

1-ethoxyurea

2-hydroxyethylurea

N-(2-hydroxypropyl)urea

N-(3-hydroxypropyl)urea

N-(2-dimethylaminopropyl)urea

N-(3-dimethylaminopropyl)urea

1-(3-hydroxyphenyl)urea

N-carbamoylmaleimide

N-carbamoylmaleamic acid

1-piperidinecarboxamide

1,2,4-triazol-4-ylurea

hydantoic acid

acetylurea

2-hydroxyethyleneurea

2-(hydroxyethyl)ethyleneurea

N-allyl-N′-ethylurea

diallylurea

2-chloroethylurea

N,N-dimethylurea

1,3-dimethylurea

1,3-diethylurea

1,3-bis(2-hydroxyethyl)urea

1,3-dipropylurea

1-ethyl-3-propylurea

N-acetyl-N′-methylurea

benzylurea

Among the compounds of formula (II) that may especially be mentioned arethe following particularly preferred compounds:

1,2-dihydro-3H-1,2,4-triazol-2-one

uracil

1-methyl-2-imidazolidinone

1,3-dimethyl-2-imidazolidinone

4,5-dihydroxyimidazolidin-2-one

1-(2-hydroxyethyl)-2-imidazolidinone

4,5-dihydroxy-1,3-dimethylimidazolidin-2-one

1,3-bis(2-hydroxyethyl)-2-imidazolidinone

2-imidazolidone-4-carboxylic acid

1-(2-aminoethyl)-2-imidazole

hydantoin

5-hydroxymethylhydantoin

hydantoin 5-acetic acid

urazole

orotic acid

dihydroxyorotic acid

2,4,5-trihydroxypyrimidine

4,5-diamino-2,6-dihydroxypyrimidine

2,4-dihydroxypyrimidine-5-carboxylic acid

5-methyl-1,3,5-triazinan-2-one

1,3-dimethyl-3,4,5,6-tetrahydro-2-1H-pyrimidinone

N-carbamoylmaleamic acid

alloxan monohydrate

As “guanidine” that may be used as relaxing active agent, this termmeans any derivative comprising in its chemical formula at least onecarbon atom doubly bonded to a nitrogen atom and singly bonded to twoother nitrogen atoms. These guanidines are more particularly selectedfrom the compounds of general formula (III) below:

in which:

R1, R2, R3, R4 and R5 represent, independently:

(iii) a hydrogen atom, or

(iv) a linear or branched C1-C4 lower alkyl or alkenyl radical,optionally substituted with one or two radicals chosen from: hydroxyl,amino, dimethylamino, methoxy, ethoxy, carboxyl, carboxamide,N-methylcarboxamide or SO₃H

When R1, R2, R3 and R4 represent a hydrogen atom, R5 may also denote aradical chosen from the following: acetyl; chloroacetyl; carboxamide;methoxy; ethoxy; 1,2,4-triazolyl; cyclopentyl; methoxycarbonyl;ethoxycarbonyl; CO—CH═CH—COOH; phenyl optionally substituted with achlorine atom or a hydroxyl radical; benzyl; thiazolidone;benzimidazole; benzoxazole; benzothiazole; or C(═NH)—NR6R7 in which R6and R7 denote, independently of each other, a hydrogen atom or a linearor branched C1-C4 lower alkyl radical, optionally substituted with oneor two radicals chosen from: hydroxyl, amino, dimethylamino, carboxyland carboxamide; or N-methylcarboxamide; or alternatively a phenylradical.

When R1=R2=R3=H, R4 and R5 may also form, with the nitrogen atom thatbears them, a pyrrolidine, piperidine, pyrazole or 1,2,4-triazole ring,optionally substituted with one or two radicals chosen from: hydroxyl,amino and carboxyl.

When R1=R2=H, and R4=H or methyl, R3 and R5 may also together form a5-membered ring optionally containing an oxo group

and the organic or mineral salts thereof.

Among the compounds of formula (III) that may especially be mentionedare the following preferred compounds:

guanidine hydrochloride guanidine acetate

guanidine sulfate

guanidine carbonate

guanidine bicarbonate

guanidine phosphate

guanidine sulfamate

aminoguanidine

aminoguanidine hydrochloride

aminoguanidine sulfate

aminoguanidine bicarbonate

1,3-diaminoguanidine hydrochloride

1-acetylguanidine

chloroacetylguanidine hydrochloride

guanylurea

guanylurea phosphate

phenylguanidine carbonate

phenylguanidine bicarbonate

1-methylguanidine hydrochloride

1,1-dimethylguanidine hydrochloride

1-ethylguanidine hydrochloride

1,1-diethylguanidine hydrochloride

creatine.

creatine monohydrate

creatinine hydrochloride

agmatine

agmatine sulfate

guanidinoacetic acid

guanidinosuccinic acid

3-guanidinopropionic acid

4-guanidinobutyric acid

5-guanidinovaleric acid

beta-N-methylguanidinopropionic acid

N-methylguanidinopropionic acid

N-(2-hydroxyethyl)guanidine

N-(3-hydroxypropyl)guanidine

biguanide hydrochloride

N-methylbiguanide hydrochloride

N-ethylbiguanide hydrochloride

N-propylbiguanide hydrochloride

N-butylbiguanide hydrochloride

1,1-dimethylbiguanide hydrochloride

1-phenylbiguanide

1,1,3,3-tetramethylguanidine hydrochloride

2-tert-butyl-1,1,3,3-tetramethylguanidine hydrochloride

L-arginine

D-arginine

DL-arginine

arginic acid

N-amidino-N-(2,3-dihydroxypropyl)glycine

N-amidinotaurine

2-imino-1-imidazolidineacetic acid

1-(2,2-diethoxyethyl)guanidine

1H-pyrazole-1-carboxamidine hydrochloride

5-hydroxy-3-methyl-1H-pyrazole-1-carboximidamide

3,5-diamino-1H-1,2,4-triazole-1-carboximidamide hydrochloride

2-guanidone-4-thiazolidone

2-guanidinobenzimidazole

2-guanidinobenzoxazole

2-guanidinobenzothiazole

pyrrolidinoformamidine hydrochloride

Among the compounds of formula (III) that may especially be mentionedare the following particularly preferred compounds:

guanidine hydrochloride

guanidine acetate

guanidine sulfate

guanidine carbonate

guanidine bicarbonate

guanidine phosphate

guanidine sulfamate

aminoguanidine hydrochloride

aminoguanidine sulfate

aminoguanidine bicarbonate

1,3-diaminoguanidine hydrochloride

guanylurea phosphate

1-methylguanidine hydrochloride

1,1-dimethylguanidine hydrochloride

1-ethylguanidine hydrochloride

creatine monohydrate

creatinine hydrochloride

agmatine

agmatine sulfate

guanidinoacetic acid

guanidinosuccinic acid

3-guanidinopropionic acid

beta-N-methylguanidinopropionic acid

N-methylguanidinopropionic acid

N-(2-hydroxyethyl)guanidine

N-(3-hydroxypropyl)guanidine

biguanide hydrochloride

N-methylbiguanide hydrochloride

N-ethylbiguanide hydrochloride

1,1-dimethylbiguanide hydrochloride

1,1,3,3-tetramethylguanidine hydrochloride

2-tert-butyl-1,1,3,3-tetramethylguanidine hydrochloride

L-arginine

DL-arginine

arginic acid

N-amidino-N-(2,3-dihydroxypropyl)glycine

N-amidinotaurine

2-imino-1-imidazolidineacetic acid

1H-pyrazole-1-carboxamidine hydrochloride

3,5-diamino-1H-1,2,4-triazole-1-carboximidamide hydrochloride

2-guanidone-4-thiazolidone

In the compositions according to the invention, the urea of formula (I)or (II) or the guanidine of formula (III) is advantageously present in amolar concentration of between 1M and 8M and more advantageously at aconcentration of between 2M and 8M. Of course, any combination of two ormore active agents can be used in combination herein.

The pH of the compositions according to the invention is preferablybetween 3 and 10 and more particularly between 5 and 9.

Advantageously, in the compositions of the invention, the urea offormula (I) or (II) or the guanidine of formula (III) is the solerelaxing active agent.

The compositions according to the invention are preferably either in theform of an aqueous solution or in the form of a thickened cream so as tokeep the hair as straight as possible. These creams are preferably madein the form of “heavy” emulsions.

For the purpose of improving the cosmetic properties of keratin fibresor alternatively of attenuating or avoiding their degradation, thecomposition used according to the invention may also comprise one ormore additional cosmetic active agents.

Generally, the additional cosmetic active agent(s) represent(s) from0.01% to 30% and preferably from 0.1% to 10% by weight relative to thetotal weight of the cosmetic composition.

Generally, the composition applied to the keratin fibres is applied at arate of from 0.05 to 20 g and preferably from 0.1 to 10 g of compositionper gram of dry keratin fibre.

In a preferred embodiment, after applying the composition, and beforeraising the temperature of the keratin fibres using a heater or heatingmeans, the composition may be left to stand on the fibres, generally forbetween 30 seconds and 60 minutes and preferably 5 to 45 minutes.

The process according to the invention comprises, preferably afterapplying the composition, raising the temperature of the keratin fibresto a temperature of between 110° C. and 250° C.

Advantageously, an iron is used as a heater or heating means.

For the purposes of the present invention, the term “iron” means adevice for heating keratin fibres by placing the fibres and the heatingdevice in contact.

The end of the iron that comes into contact with the hair generally hastwo flat surfaces. These two flat surfaces may be metallic. They may besmooth or notched.

As examples of irons that may be used in the process according to theinvention, mention may preferably be made of any type of flat iron andin particular, in a non-limiting manner, those described in U.S. Pat.No. 5,957,140 and U.S. Pat. No. 5,046,516.

The application of the iron may be performed by successive touchesseparated by a few seconds, or by gradual moving or sliding along locks,etc.

Preferably, the application of the iron in the process according to theinvention is performed by continuous movement from the root to the end,in one or more passes.

The process according to the invention may also comprise partialpredrying of the keratin fibres before raising the temperature, so as toavoid substantial release of steam that might burn the hands of thehairstylist and the individual's scalp. This predrying step may beperformed, for example, using a hairdryer, a drying hood or by freedrying.

EXAMPLES

The invention will be understood more clearly with the aid of thenon-limiting examples that follow, which constitute preferredembodiments of the invention.

Example 1

A simplified relaxing composition containing urea, at a concentration of8M in water, as relaxing active agent is prepared. The pH of thecomposition is 8.06. This composition is applied to naturally frizzyAfrican hair for 15 minutes at a temperature of 40° C. and the hair isthen rapidly wiped with a towel.

The hair is then straightened lock by lock using a flat iron heated to180° C. for 5 to 10 seconds. The hair is efficiently relaxed and feelssoft.

Example 2

A simplified relaxing composition containing urea, at a concentration of4M in water, as relaxing active agent is prepared. The pH of thecomposition is 7.7. This composition is applied to naturally frizzyAfrican hair for 25 minutes at a temperature of 40° C. and the hair isthen rapidly wiped with a towel.

The hair is then straightened lock by lock using a flat iron heated to180° C., for 5 to 10 seconds. The hair is efficiently relaxed and feelssoft.

Example 3

A simplified relaxing composition containing guanidine hydrochloride, ata concentration of 8M in water, as relaxing active agent is prepared.The pH of the composition is 5.46. This composition is applied tonaturally frizzy African hair for 15 minutes, at a temperature of 40° C.and the hair is then rapidly wiped with a towel.

The hair is then straightened lock by lock using a flat iron heated to180° C., for 5 to 10 seconds. The hair is efficiently relaxed and feelssoft.

The invention process for relaxing keratin fibres includes hairrelaxing, uncurling and straightening, etc. While the invention can bethought of as involving distinct acts, such as

(i) applying to the keratin fibres a relaxing composition containing atleast one denaturing agent with a molecular mass of greater than 18.1g/mol, present in a molar concentration of between 1M and 8M, and

(ii) raising the temperature of the keratin fibres, using a heater orheating means, to a temperature of between 110 and 250° C.,

it can also be thought of as a method comprising raising the temperatureof keratin fibres, using a heater or heating means, to a temperature ofbetween 110 and 250° C. wherein said keratin fibres comprise on at leasta part of a surface thereof at least one denaturing agent with amolecular mass of greater than 18.1 g/mol.

The above written description of the invention provides a manner andprocess of making and using it such that any person skilled in this artis enabled to make and use the same, this enablement being provided inparticular for the subject matter of the appended claims, which make upa part of the original description and including a process for relaxingkeratin fibres comprising:

(i) applying to the keratin fibres a relaxing composition comprising,consisting essentially of, or consisting of, at least one denaturingagent with a molecular mass of greater than 18.1 g/mol, present in amolar concentration of between 1M and 8M, and

(ii) raising the temperature of the keratin fibres to a temperature ofbetween 110 and 250° C., as well as a method comprising raising thetemperature of keratin fibres to a temperature of between 110 and 250°C. wherein said keratin fibres comprise on at least a part of a surfacethereof at least one denaturing agent with a molecular mass of greaterthan 18.1 g/mol.

As used above, the phrases “selected from the group consisting of,”“chosen from,” and the like include mixtures of the specified materials.

All references, patents, applications, tests, standards, documents,publications, brochures, texts, articles, etc. mentioned herein areincorporated herein by reference. Where a numerical limit or range isstated, the endpoints are included. Also, all values and subrangeswithin a numerical limit or range are specifically included as ifexplicitly written out. Terms such as “contain(s)” and the like as usedherein are open terms meaning ‘including at least’ unless otherwisespecifically noted.

The above description is presented to enable a person skilled in the artto make and use the invention, and is provided in the context of aparticular application and its requirements. Various modifications tothe preferred embodiments will be readily apparent to those skilled inthe art, and the generic principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the invention. Thus, this invention is not intended to belimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

1. A process for relaxing keratin fibres comprising: (i) applying to thekeratin fibres a relaxing composition comprising at least one denaturingagent with a molecular mass of greater than 18.1 g/mol, present in amolar concentration of between 1M and 8M, to provide treated keratinfibers, and (ii) raising the temperature of the treated keratin fibresto a temperature of between 110 and 250° C.
 2. The process according toclaim 1, wherein the relaxing composition comprises between 2M and 8M ofthe said denaturing agent.
 3. The process according to claim 1, whereinthe temperature is raised to a temperature of between 120° C. and 220°C.
 4. The process according to claim 1, wherein the molar mass of thedenaturing agent is between 40 and 600 g/mol.
 5. The process accordingto claim 1, wherein the composition is applied to wet keratin fibres. 6.The process according to claim 1, wherein the treated fibres arepartially predried prior to raising the temperature of the treatedkeratin fibres.
 7. The process according to claim 1, wherein therelaxing composition comprises at least one protein-denaturing agentselected from ureas, guanidines, aromatic monohydroxylated,dihydroxylated, trihydroxylated or polyhydroxylated derivatives,carboxylic acids and derivatives thereof, amino acids, alcohols, amineoxides, surfactants containing sugar, choline, deoxycholine orpolyethylene glycol units, metal salts and sulfamides.
 8. The processaccording to claim 1, wherein the composition comprises urea.
 9. Theprocess according to claim 1, wherein the composition comprises at leastone compound that corresponds to formula (I):

in which: R1, R2, R3 and R4 represent, independently: (v) a hydrogenatom, or (vi) a linear or branched lower C1-C4 alkyl or alkenyl radical,optionally substituted with a radical chosen from: hydroxyl, amino,dimethylamino, carboxyl or carboxamide or N-methylcarboxamide when R1,R2 and R3 represent a hydrogen atom, R4 may also denote a radical chosenfrom the following: carboxamide; methoxy; ethoxy; 1,2,4-tri-azolyl;cyclopentyl; methoxycarbonyl; ethoxycarbonyl; CO—CH═CH—COOH; phenyloptionally substituted with a chlorine atom or a hydroxyl radical;benzyl; or 2,5-dioxo-4-imidazolidinyl when R1 and R3 represent ahydrogen atom, R2 may also represent a hydrogen atom or a methyl orethyl radical and R4 an acetyl radical when R1=R2=H, R3 and R4 may alsoform, with the nitrogen atom that bears them, a piperidine or3-methylpyrazole or 3,5-dimethylpyrazole or maleimide ring R1 and R2,and also R3 and R4, may also form, with the nitrogen atom that bearsthem, an imidazole ring.
 10. The process according to claim 1, whereinthe composition comprises at least one compound that corresponds toformula (II):

in which: R5 and R6 represent, independently of each other: (iii) ahydrogen atom, or (iv) a linear or branched C1-C4 lower alkyl radical,optionally substituted with a radical chosen from: hydroxyl, amino,dimethylamino, carboxyl or carboxamide, and A represents the radicals:CH2-CH2 or CH═CH or CH2-CO or CO—NH or CH═N or CO—CO or CHOH—CHOH or(HOOC)CH—CH or CHOH—CO or CH2-CH2-CH2 or CH2-NH—CO or CH═C(CH3)—CO orNH—CO—NH or CH2-CH2-CO or CH2-N(CH3)—CH2 or NH—CH2-NH or CO—CH(CH3)—CH2or CO—CH2-CO or CO—NH—CO or CO—CH(COOH)—CH2 or CO—CH═C(COOH) orCO—CH═C(CH3) or CO—C(NH2)═CH or CO—C(CH3)═N or CO—CH═CH or CO—CH═N orCO—N═CH.
 11. The process according to claim 1, wherein the compositioncomprises at least one compound chosen from: urea methylurea ethylureapropylurea isopropylurea n-butylurea sec-butylurea isobutylureatert-butylurea cyclopentylurea 1-ethoxyurea 2-hydroxyethylureaN-(2-hydroxypropyl)urea N-(3-hydroxypropyl)ureaN-(2-dimethylaminopropyl)urea N-(3-dimethylaminopropyl)urea1-(3-hydroxyphenyl)urea benzylurea N-carbamoylmaleimide biuretN-carbamoylmaleamic acid 1-piperidinecarboxamide 1,2,4-triazol-4-ylureahydantoic acid methyl allophanate ethyl allophanate acetylurea2-hydroxyethyleneurea 2-(hydroxyethyl)ethyleneurea N-allyl-N′-ethylureadiallylurea 2-chloroethylurea N,N-dimethylurea N,N-diethylureaN,N-dipropylurea 1-cyclopentyl-1-methylurea 1,3-dimethylurea1,3-diethylurea 1,3-bis(2-hydroxyethyl)urea 1,3-bis(2-hydroxypropyl)urea1,3-bis(3-hydroxypropyl)urea 1,3-dipropylurea 1-ethyl-3-propylurea1-sec-butyl-3-methylurea 1-isobutyl-3-methylurea1-cyclopentyl-3-methylurea N-acetyl-N′-methylurea trimethylurea1-butyl-3,3-dimethylurea tetramethylurea and benzylurea.
 12. The processaccording to claim 1, wherein the composition comprises at least onecompound chosen from: parabanic acid 1,2-dihydro-3-H-1,2,4-triazol-2-onebarbituric acid uracil 1-methyluracil 3-methyluracil 5-methyluracil1,3-dimethyluracil 5-azauracil 6-azauracil 5-fluorouracil 6-fluorouracil1,3-dimethyl-5-fluorouracil 5-aminouracil 6-aminouracil6-amino-1-methyluracil 6-amino-1,3-dimethyluracil 4-chlorouracil5-chlorouracil 5,6-dihydrouracil 5,6-dihydro-5-methyluracil2-imidazolidone hydrate 1-methyl-2-imidazolidinone1,3-dimethyl-2-imidazolidinone 4,5-dihydroxyimidazolidin-2-one1-(2-hydroxyethyl)-2-imidazolidinone1-(2-hydroxypropyl)-2-imidazolidinone1-(3-hydroxypropyl)-2-imidazolidinone4,5-dihydroxy-1,3-dimethylimidazolidin-2-one1,3-bis(2-hydroxyethyl)-2-imidazolidinone 2-imidazolidone-4-carboxylicacid 1-(2-aminoethyl)-2-imidazole 4-methyl-1,2,4-triazoline-3,5-dione2,4-dihydroxy-6-methylpyrimidine 1-amino-4,5-dihydro-1H-tetrazol-5-onehydantoin 1-methylhydantoin 5-methylhydantoin 5,5-dimethylhydantoin5-ethylhydantoin 5-n-propylhydantoin 5-ethyl-5-methylhydantoin5-hydroxy-5-methylhydantoin 5-hydroxymethylhydantoin 1-allylhydantoin1-aminohydantoin hydantoin 5-acetic acid4-amino-1,2,4-triazolone-3,5-dione hexahydro-1,2,4,5-tetrazine-3,6-dione5-methyl-1,3,5-triazinon-2-one 1-methyltetrahydropyrimidin-2-one2,4-dioxohexahydro-1,3,5-triazine urazole 4-methylurazole orotic aciddihydroxyorotic acid 2,4,5-trihydroxypyrimidine2-hydroxy-4-methylpyrimidine 4,5-diamino-2,6-dihydroxypyrimidinebarbituric acid 1,3-dimethylbarbituric acid cyanuric acid1-methylhexahydropyrimidine-2,4-dione1,3-dimethyl-3,4,5,6-tetrahydro-2-1H-pyrimidinone5-(hydroxymethyl-2,4-(1H,3H)-pyrimidinedione2,4-dihydroxypyrimidine-5-carboxylic acid 6-azathymine5-methyl-1,3,5-triazinan-2-one N-carbamoylmaleamic acid and alloxanmonohydrate.
 13. The process according to claim 1, wherein thecomposition comprises at least one compound that corresponds to formula(III) below:

in which: R1, R2, R3, R4 and R5 represent, independently: (vii) ahydrogen atom, or (viii) a linear or branched C1-C4 lower alkyl oralkenyl radical, optionally substituted with one or two radicals chosenfrom: hydroxyl, amino, dimethylamino, methoxy, ethoxy, carboxyl,carboxamide, N-methylcarboxamide or SO₃H when R1, R2, R3 and R4represent a hydrogen atom, R5 may also denote a radical chosen from thefollowing: acetyl; chloroacetyl; carboxamide; methoxy; ethoxy;1,2,4-triazolyl; cyclopentyl; methoxycarbonyl; ethoxycarbonyl;CO—CH═CH—COOH; phenyl optionally substituted with a chlorine atom or ahydroxyl radical; benzyl; thiazolidone; benzimidazole; benzoxazole;benzothiazole; or C(═NH)—NR6R7 in which R6 and R7 denote, independentlyof each other, a hydrogen atom or a linear or branched C1-C4 lower alkylradical, optionally substituted with one or 2 radicals chosen from:hydroxyl, amino, dimethylamino, carboxyl and carboxamide; orN-methylcarboxamide; or alternatively a phenyl radical when R1=R2=R3=H,R4 and R5 may also form, with the nitrogen atom that bears them, apyrrolidine, piperidine, pyrazole or 1,2,4-triazole ring, optionallysubstituted with 1 or 2 radicals chosen from: hydroxyl, amino andcarboxyl when R1=R2=H, and R4=H or methyl, R3 and R5 may also togetherform a 5-membered ring optionally containing an oxo group and theorganic or mineral salts thereof.
 14. The process according to claim 1,wherein the composition comprises at least one compound chosen from:guanidine hydrochloride guanidine acetate guanidine sulfate guanidinecarbonate guanidine bicarbonate guanidine phosphate guanidine sulfamateaminoguanidine aminoguanidine hydrochloride aminoguanidine sulfateaminoguanidine bicarbonate 1,3-diaminoguanidine hydrochloride1-acetylguanidine chloroacetylguanidine hydrochloride guanylureaguanylurea phosphate phenylguanidine carbonate phenylguanidinebicarbonate 1-methylguanidine hydrochloride 1,1-dimethylguanidinehydrochloride 1-ethylguanidine hydrochloride 1,1-diethylguanidinehydrochloride creatine creatine monohydrate creatinine hydrochlorideagmatine agmatine sulfate guanidinoacetic acid guanidinosuccinic acid3-guanidinopropionic acid 4-guanidinobutyric acid 5-guanidinovalericacid beta-N-methylguanidinopropionic acid N-methylguanidinopropionicacid N-(2-hydroxyethyl)guanidine N-(3-hydroxypropyl)guanidine biguanidehydrochloride N-methylbiguanide hydrochloride N-ethylbiguanidehydrochloride N-propylbiguanide hydrochloride N-butylbiguanidehydrochloride 1,1-dimethylbiguanide hydrochloride 1-phenylbiguanide1,1,3,3-tetramethylguanidine hydrochloride2-tert-butyl-1,1,3,3-tetramethylguanidine hydrochloride L-arginineD-arginine DL-arginine arginic acidN-amidino-N-(2,3-dihydroxypropyl)glycine N-amidinotaurine2-imino-1-imidazolidineacetic acid 1-(2,2-diethoxyethyl)guanidine1H-pyrazole-1-carboxamidine hydrochloride5-hydroxy-3-methyl-1H-pyrazole-1-carboximidamide3,5-diamino-1H-1,2,4-triazole-1-carboximidamide hydrochloride2-guanidone-4-thiazolidone 2-guanidinobenzimidazole2-guanidinobenzoxazole 2-guanidinobenzothiazole andpyrrolidinoformamidine hydrochloride.
 15. The process according to claim1, wherein the temperature of the treated keratin fibres is raised to atemperature of between 110 and 250° C. with a heater.
 16. The processaccording to claim 1, wherein the temperature of the treated keratinfibres is raised to a temperature of between 110 and 250° C. with aheating means.
 17. The process according to claim 15, wherein thetemperature of the treated keratin fibres is raised to a temperature ofbetween 110 and 250° C. with an iron.
 18. The process according to claim1, wherein said composition is in the form of an aqueous solution or inthe form of a thickened cream.
 19. A process comprising raising thetemperature of keratin fibres to a temperature of between 110 and 250°C., wherein said keratin fibres comprise on at least a part of a surfacethereof at least one denaturing agent with a molecular mass of greaterthan 18.1 g/mol.
 20. The process according to claim 19, wherein thetemperature of the keratin fibres is raised to a temperature of between110 and 250° C. with an iron.